The latest medical research on Immunology & Allergy

The research magnet gathers the latest research from around the web, based on your specialty area. Below you will find a sample of some of the most recent articles from reputable medical journals about immunology & allergy gathered by our medical AI research bot.

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Mitochondria and ageing with HIV.

Current Opinion in Cell Biology

Some older people living with HIV (PLWH) exhibit features of unsuccessful ageing, such as frailty. Mitochondrial dysfunction is one of the best characterized ageing mechanisms. There has been recent interest in whether some people ageing with HIV may have an excess of mitochondrial dysfunction. This review aims to address this question through: analogy with ageing and chronic disease; discussion of the key unknowns; suggested ways that measures of mitochondrial dysfunction might be incorporated into HIV research studies.

Recent data suggest that mitochondrial dysfunction in PLWH may not be wholly a legacy effect of historical nucleoside analog reverse transcriptase inhibitor exposures. Research in the non-HIV setting has altered our understanding of the important mediators of mitochondrial dysfunction in ageing.

Mitochondrial dysfunction is a very plausible driver of adverse ageing phenotypes in some older PLWH. As such it may be a target for therapeutic interventions. Currently, however, there remain considerable uncertainties around the extent of this phenomenon, and its relative importance. Current studies are likely to clarify these questions over the next few years.

National HIV testing and diagnosis coverage in sub-Saharan Africa: a new modeling tool for estimating the "first 90" from program and survey data.

AIDS

HIV testing services (HTS) are a crucial component of national HIV responses. Learning one's HIV diagnosis is the entry point to accessing life-saving antiretroviral treatment and care. Recognizing the critical role of HTS, the Joint United Nations Programme on HIV/AIDS (UNAIDS) launched the 90-90-90 targets stipulating that by 2020, 90% of people living with HIV know their status, 90% of those who know their status receive antiretroviral therapy, and 90% of those on treatment have a suppressed viral load. Countries will need to regularly monitor progress on these three indicators. Estimating the proportion of people living with HIV who know their status (i.e., the "first 90"), however, is difficult.

We developed a mathematical model (henceforth referred to as "F90") that formally synthesizes population-based survey and HTS program data to estimate HIV status awareness over time. The proposed model uses country-specific HIV epidemic parameters from the standard UNAIDS Spectrum model to produce outputs that are consistent with other national HIV estimates. The F90 model provides estimates of HIV testing history, diagnosis rates, and knowledge of HIV status by age and sex. We validate the F90 model using both in-sample comparisons and out-of-sample predictions using data from three countries: Côte d'Ivoire, Malawi, and Mozambique.

In-sample comparisons suggest that the F90 model can accurately reproduce longitudinal sex-specific trends in HIV testing. Out-of-sample predictions of the fraction of PLHIV ever tested over a 4-to-6-year time horizon are also in good agreement with empirical survey estimates. Importantly, out-of-sample predictions of HIV knowledge are consistent (i.e., within 4% points) with those of the fully calibrated model in the three countries when HTS program data are included. The F90 model's predictions of knowledge of status are higher than available self-reported HIV awareness estimates, however, suggesting -in line with previous studies- that these self-reports could be affected by non-disclosure of HIV status awareness.

Knowledge of HIV status is a key indicator to monitor progress, identify bottlenecks, and target HIV responses. The F90 model can help countries track progress towards their "first 90" by leveraging surveys of HIV testing behaviors and annual HTS program data.

Parameter estimates for trends and patterns of excess mortality among persons on ART in high-income european settings.

AIDS

HIV cohort data from high-income European countries were compared to the UNAIDS Spectrum modelling parameters for these same countries to validate mortality rates and excess mortality estimates for people living with HIV (PLHIV) on antiretroviral therapy (ART).

Data from 2000-2015 were analysed from the Antiretroviral Therapy Cohort Collaboration (ART-CC) for Austria, Denmark, France, Italy, the Netherlands, Spain, and Switzerland. Flexible parametric models were used to compare All-cause mortality rates in the ART-CC and Spectrum. The percentage of AIDS-related deaths and excess mortality (both are the same within Spectrum) were compared, with excess mortality defined as that in excess of the general population mortality.

Analyses included 94026 PLHIV with 585784 person-years of follow-up, from which there were 5515 deaths. All-cause annual mortality rates in Spectrum for 2000-2003 were 0.0121, reducing to 0.0078 in 2012-2015, whilst the ART-CC's corresponding annual mortality rates were 0.0151 (95% confidence interval [95%CI]: 0.0130-0.0171) reducing to 0.0049 (95%CI: 0.0039-0.0060). The percentage of AIDS-related deaths in Spectrum was 74.7% in 2000-2003, dropping to 43.6% in 2012-15. In the ART-CC, AIDS-related mortality comprised 45.3% (95%CI: 38.4%-52.9%) of mortality in 2000-2003 and 26.7% (95%CI: 19.0%, 46.0%) between 2012-2015. Excess mortality in the ART-CC was broadly similar to the Spectrum estimates, dropping from 75.3% (95%CI: 60.3%-95.2%) in 2000-2003 to 30.7% (95%CI: 25.5%-63.7%) in 2012-2015.

All-cause mortality assumptions for PLHIV on ART in high-income European settings should be adjusted in Spectrum to be higher in 2000-2003 and decline more quickly to levels currently captured for recent years.

Use of the dapivirine vaginal ring and effect on cervical cytology abnormalities.

AIDS

We aimed to determine if the dapivirine vaginal ring and the ring device alone (flexible silicone matrix polymer) was associated with the development of cervical cytology abnormalities.

Secondary analysis comparing cervical cytology results between two randomized controlled microbicide trials (ASPIRE and VOICE) METHODS:: Data from the MTN-020/ASPIRE, a phase III, placebo-controlled trial of the dapivirine vaginal ring, were used in this analysis. Cervical cytology smears were evaluated at baseline and at the final visit with product use. We compared cytology results between women randomized to dapivirine versus placebo vaginal ring. We further assessed for the effect of the vaginal ring device on cervical cytology by comparing results with data from the oral placebo arm of MTN-003/VOICE, a prior HIV-1 prevention trial conducted in a similar population.

Cervical cytology results for 2394 women from ASPIRE (1197 per study arm) were used in this analysis; median time between baseline and final visit with product use was 22.1 months. Cytology smear findings were comparable between dapivirine and placebo vaginal ring arms: at final visit, normal: 90.6% vs. 91.5%, ASC-US//LSIL: 7.8% vs. 7.4%, ASC-H/HSIL/AGC/AGC-favor neoplastic: 1.7% vs. 1.1%, p = 0.44. Cytology data from VOICE had findings (normal: 87.8%, ASC-US/LSIL: 9.8%, ASC-H/HSIL/AGC/AGC-favor neoplastic: 2.4%) comparable to that of both dapivirine (p = 0.93) and placebo vaginal ring arms (p = 0.24).

These findings indicate that neither use of the dapivirine vaginal ring nor the vaginal ring device alone, over a period of two years, is associated with development of cervical cytology abnormalities that could lead to pre-cancerous or cancerous lesions.

Virological and immunological impact of integrase inhibitor-based regimens initiated during primary HIV-1 infection.

AIDS

This study was conducted among patients who initiated cART between 2013 and 2017, using data from the ANRS-PRIMO cohort and the Dat'AIDS study. Cumulative proportions of patients reaching viral suppression (HIV-1 RNA <50 cp/mL) were calculated using Turnbull's estimator for interval-censored data. CD4 cells and CD4/CD8 ratio increases were estimated using mixed linear models. Results were adjusted for the data source.

Among the 712 study patients, 299 received an INSTI-based cART. Patients baseline characteristics were similar between groups. Viral suppression was reached more rapidly in INSTI- versus PI/r-treated patients (p < 0.01), with cumulative proportions of 37% vs 6% at 4 weeks, 77% vs 38% at 12 weeks, 92% vs 79% at 24 weeks and 93% in both groups at 48 weeks. At 4 weeks, INSTI-treated patients had gained on average 40 CD4 cells/μl (p=0.05) over PI/r-treated ones; mean CD4 counts were similar in the two groups at 48 weeks. The CD4/CD8 ratio followed the same pattern. Results were similar when restricted to a comparison between Dolutegravir- vs Darunavir-based cART.

Based on this study and available literature, we recommend the use of INSTI-based cART for treatment initiation during PHI, since it leads to faster viral suppression and immune restoration.

Kaposi sarcoma in people living with HIV: incidence and associated factors in the French DAT'AIDS cohort between 2010 and 2015.

AIDS

Kaposi sarcoma (KS) is still observed among people living with HIV (PLHIV) including those on ART with undetectable HIV viral load (HIV-VL). We aimed to assess KS incidence and trends between 2010 and 2015 in France and to highlight associated factors.

Demographic, immunological, and therapeutic characteristics collected at time of KS diagnosis or at last visit for patients without KS.

Among 180 216.4 person-years (PY), KS incidence was 76.0 [95% CI 64.3-89.9]/10 PY. Multivariate analysis (Poisson regression) revealed the positive association with male gender, men who have sex with men (MSM) transmission route, lower CD4 T cell count, higher CD8 T cell count, not to be on ART, while HIV follow-up time, duration with an HIV-VL≤50 copies/mL were negatively associated with KS. According to the different models tested, HIV-VL, CD4:CD8 ratio and nadir CD4 cell count were associated with KS. Moreover, stratified analysis showed that patients with a CD4:CD8 ratio≤0.5 or a CD8 T cell count>1000/mm were at higher risk of KS regardless of the CD4 T cell count.

This study showed that in a resource-rich country setting with high ART coverage, KS still occurred among PLWH. CD8 hyperlymphocytosis and CD4:CD8 ratio should be now considered as two useful markers to better identify patients at increased KS risk, including those with a CD4 T cell count > 500/mm.

Presence of EBV DNA in Cerebrospinal Fluid is Associated with Greater HIV RNA and Inflammation.

AIDS

This study aimed to investigate whether cerebrospinal fluid (CSF) EBV or CMV DNA was associated with viral, inflammatory and neuronal damage biomarkers in people living with HIV (PLWH).

EBV, CMV DNA and HIV RNA were measured on CSF, through RT-PCR, from PLWHs undergoing lumbar punctures for clinical reasons (excluding oncho-haematological comorbidities). Immune-enzymatic assays evaluated BBB inflammation and damage. Patients were stratified according to plasma HIV RNA levels in viremic (≥50 copies/mL) and aviremic (<50 copies/mL).

We included 297 participants. Among 167 viremic patients CSF EBV and CMV DNA were detectable in 42 (25.1%) and 10 (6.3%) participants; among 130 aviremic subjects CSF EBV and CMV DNA were detectable in 12 (9.2%) and 0 (0%) participants, respectively. In viremic group detectable CSF EBV DNA was associated with CSF pleocytosis (p < 0.001), higher CSF HIV RNA (p < 0.001) and neopterin levels (p = 0.002). In aviremic participants detectable EBV DNA was associated with pleocytosis (p = 0.056), higher neopterin (p = 0.027) and immune globulins (p = 0.016) in the CSF; CSF escape was more common in those with detectable EBV DNA (50% vs 21.2%, p = 0.036).

EBV DNA was frequently detected in the CSF of viremic and fewer aviremic patients on antiretroviral treatment. In PLWH without clinical evidence of encephalitis CSF EBV DNA was associated with higher biomarkers levels of neuronal damage/inflammation. The role of EBV reactivation in HIV-associated CNS disorders warrants further studies.

Activated PD-1+ CD4 T cells represent a short-lived part of the viral reservoir and predict poor immunologic recovery upon initiation of ART.

AIDS

Activated (CD38+HLA-DR+) PD-1+ CD4 T cells are strongly associated with virus replication and disease progression in untreated HIV-1 infection, and viral persistence in individuals on ART. Few studies have examined cell associated viral load (CAVL) in different activated CD4 T cell populations to measure relative contributions to viral reservoirs.

We followed 32 HIV-1 chronically infected individuals from Kampala, Uganda, and determined their CD4 T cell counts and viral load at baseline, 6, and 12 months after the initiation of ART. T cell populations were sorted based on activation profiles and gag DNA was measured to determine CAVL within these populations. Soluble factors associated with inflammation were measured in plasma using a multiplexed platform.

Concomitant with viral load decline and CD4 T cell count rebound, the activated PD-1+ CD4 T cell population contracted upon initiation of ART. Baseline levels of activated PD-1+ CD4 T cells correlated with plasma levels of IP-10 and TNFRII. Interestingly, higher baseline level of activated PD-1+ CD4 T cells was associated with poorer CD4 T cell recovery after 12 months of ART. This population contributed significantly to the cell-associated HIV DNA load at baseline, whereas their contribution declined on ART, indicating high turnover.

Activated PD-1+ CD4 T cells are predictors of poor immunologic recovery on ART and may represent a short-lived component of HIV-1 reservoirs.

Left ventricular diastolic dysfunction in HIV-uninfected infants exposed in utero to antiretroviral therapy.

AIDS

To longitudinally measure LV diastolic function in HIV-exposed but uninfected (HEU) children perinatally-exposed to ART.

Serial echocardiograms were obtained at specific times from birth to 48 months from two groups of HIV-uninfected children: 148 HIV-negative children who were perinatally-exposed to ART and 130 non-ART-exposed HIV-unexposed healthy controls. The following LV diastolic indices were obtained: mitral valve early and late diastolic velocity (E and A), tissue Doppler derived LV free wall and septal early diastolic velocity (LVe' and sep e').

All echocardiographic indices were significantly different in ART-exposed children compared to ART-unexposed healthy controls. Both E and A were overall lower at all ages by 8.28 cm/sec (P = 0.0002) and 13.46 cm/sec (P < 0.0001) respectively. E/A ratio was higher by 0.27, 0.46, and 0.28 units at birth, 1 year and 2 years of age, respectively (all P ≤ 0.01). Moreover, LVe' and sep e' were overall lower at all ages by 0.84 cm/sec (P = 0.01) and 0.47 cm/sec (P = 0.02) respectively.

Children who were exposed to ART in utero have subclinical yet significant differences in specific LV diastolic indices. Follow-up with serial echocardiograms is recommended in this population to further assess the potential cardiac toxicity of perinatal exposure to ART.

Measuring the contribution of γδ T cells to the persistent HIV reservoir.

AIDS

To study the contribution of γδ T cells to the persistent HIV reservoir.

Resting αβ+CD4 T cells were magnetically isolated from PBMCs using two different custom cocktails, only one kit contained antibodies to deplete γδ T cells, resulting in two populations: rCD4 cells and rCD4 cells depleted of γδ cells. Frequency of infection was analyzed by QVOA and DNA measurements.

Recovery of replication competent HIV from cultures of rCD4 cells was similar in 11 individuals despite the presence of γδ T cells. In four donors, HIV recovery was lower when γδ T cells were present. Expression of the cytotoxic marker CD16 on Vδ2 cells was the only variable associated with the lower HIV recovery. Our results highlight the potency of those responses since a mean of 10.000 γδ T cells were present within 2.5million rCD4 cells. However, despite the low frequency of γδ T cells, the presence of cytotoxic Vδ2 cells correlated with lower HIV recovery from cultures of rCD4 cells.

Results of this study show that quantification of the contribution of γδ T cells to the reservoir is challenging due to their low numbers compared to conventional rCD4 cells and highlights the potent antiviral function of γδ T cells and the impact of their presence on the frequency of latent HIV infection.

HIV post-exposure prophylaxis-in-pocket ("PIP"): long-term follow-up of individuals with low-frequency, high-risk HIV exposures.

AIDS

HIV Pre-exposure prophylaxis and post-exposure prophylaxis are two major biomedical HIV prevention modalities. The utility of these prevention tools for individuals with infrequent high-risk HIV exposures remains uncertain. HIV post-exposure prophylaxis-in-pocket ("PIP") may be an effective HIV prevention tool in such situations. Here we present long-term follow up of a cohort of patients initiated on PIP for HIV prevention.

We retrospectively evaluated clinical characteristics of patients initiated on PIP as a primary HIV prevention tool between January 1, 2016 to May 31, 2019 at the Toronto General Hospital HIV Prevention Clinic and St. Michael's Hospital HIV Clinic, both in Toronto, Canada. Patients were referred for consideration of a biomedical HIV prevention modality. Individuals with a low frequency of high-risk exposures to HIV were initiated on PIP after counselling, and were followed at regular intervals. Demographic and clinical data was collected with a standardized form.

A total of 79 patients were initiated on PIP as a primary HIV prevention modality and followed for a mean duration of 14.8 months combining for a total of 97.3 patient-years. Twenty one (26.6%) patients used their PIP, and 32 courses of PIP were taken during the study period. Transitions between HIV prevention modalities included 13 (16.5%) patients who transitioned from PrEP to PIP, and 22 (27.8%) patients who transitioned from PIP to PrEP. No HIV seroconversions were detected during the course of this study.

PIP is helpful HIV prevention modality for individuals with a low frequency of high-risk HIV exposures.

Eligibility for differentiated models of HIV treatment service delivery: an estimate from Malawi and Zambia.

AIDS

Little is known about the proportion of HIV-positive clients on antiretroviral therapy (ART) who meet stability criteria for differentiated service delivery (DSD) models. We report the proportion of ART clients meeting stability criteria as part of screening for a randomized trial of multi-month dispensing in Malawi and Zambia.

For a DSD trial now underway, we screened HIV-positive clients ≥18 years presenting for HIV treatment in 30 adult ART clinics in Malawi and Zambia to determine eligibility for DSD. Stability was defined as on first-line ART (efavirenz/tenofovir/lamivudine) for at least six months, no ART side effects, no toxicity or infectious complications, no non-communicable diseases being treated in ART clinic, no lapses in ART adherence in the prior six months (>30 days without taking ART), and if female, not pregnant or breastfeeding.

A total of 3,465 adult ART clients were approached between May 10, 2017 and April 30, 2018 (Malawi: 1,680; Zambia: 1,785). Of the 2,938 who answered screening questions (Malawi: 1,527; Zambia: 1,411), 2,173 (73.5%) met criteria for DSD eligibility (Malawi: 72.8%; Zambia: 74.3%). The most common reasons for ineligibility were being on ART less than six months (9.6%) and a regimen other than standard first-line (7.9%).

Approximately three-quarters of all adult clients presenting at ART clinics in Malawi and Zambia were eligible for DSD using a typical definition of stability. High uptake of DSD models by eligible clients would have a major impact on the infrastructure and the allocation of HIV treatment resources.